The Internet is an increasing part of our lives. It is used at home to perform research, send and receive electronic mail, to play games, telecommute, and other such applications. In an effort to increase Internet accessibility, some individuals, businesses and/or government entities have installed wireless access points (WAP) or “Internet hotspots” that allow people to access the Internet with a wireless station (STA). Examples of STAs include laptop computers, palmtop computers, personal digital assistants (PDAs), hand-held gaming devices, and/or other such devices that can be equipped with a wireless local area network (WLAN) interface that communicates with the WAP.
Some cities, such as San Francisco, Calif., are being outfitted with a plurality of WAPs so that Internet access is practically ubiquitous throughout the city. However, such an effort requires a significant investment in WAPs along with additional and ongoing maintenance expenses. WLAN signals may be absorbed by dense structures, have limited range and may be limited to line-of-sight applications. It therefore becomes exponentially more expensive to provide a city with truly ubiquitous wireless Internet access since WAPs would need to be located in many locations that are practically shielded from the UHF and SHF bands. These locations include underground parking structures, basements, subway systems, around land masses, and so forth. Current federal rules also limit the transmitter power of WLANs in the aforementioned portions of the UHF and SHF bands to a fairly low value. Even under ideal RF propagation conditions, a city would need a large number of WAPs for a STA to move between contiguous Internet hotspots.
Referring now to FIG. 1, a WLAN 10 includes a WAP 12 that communicates with a distributed communication system 14 such as the Internet via a communication link 16. Communication link 16 can include a copper, fiber optic, wireless links, and/or the like. A STA 18 associates with WAP 12 via a wireless communication channel 20. WAP 12 and communication link 16 then complete a communication path between STA 18 and the distributed communication system 14.
Referring now to FIG. 2, a functional block diagram is shown that illustrates some of the challenges presented in establishing ubiquitous wireless access over a geographic area. A plurality of masses 22 represents buildings, land masses, and/or other barriers to the wireless communication channels 20 between WAPs 12 and STAs 18. A distance between the STA and the WAP also may present problems. A first WAP 12-1 communicates with distributed communication system 14 via a first communication link 16-1. A second WAP 12-2 communicates with distributed communication system 14 via a second communication link 16-2. A first STA 18-1 associates with a first WAP 12-1 via a wireless communication channel 20-1 that is unobstructed by one or more of masses 22. A second STA 18-2 associates with second WAP 12-2 via a wireless communication channel 20-2 that is unobstructed by one of masses 22.
A third STA 18-3 is unable to establish a wireless communication channel to nearby second WAP 12-2 since one of masses 22 lies in the way. Additional WAPs 12 such as a third WAP 12-3 would need to be installed within line-of-sight of third STA 18-3 to provide it with a link to distributed communication system 14. More WAPs would need to be provided to further extend coverage.